CN114616774B

CN114616774B - CQI-based downlink buffer management

Info

Publication number: CN114616774B
Application number: CN202080075427.1A
Authority: CN
Inventors: R·巴拉苏布拉马尼安; P·阿杜苏米利; A·基塔比; A·梅朗
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2019-11-05
Filing date: 2020-10-14
Publication date: 2024-04-30
Anticipated expiration: 2040-10-14
Also published as: CN114616774A; EP4055732A1; WO2021091665A1; US20210135727A1; EP4055732B1; US11336355B2

Abstract

Certain aspects of the present disclosure provide techniques for Channel Quality Indicator (CQI) -based downlink buffer management and mitigation of throughput loss in dual connectivity with multiple SIMs. A method that may be performed by a User Equipment (UE) includes: the method includes communicating with a first network on a first channel using a first technology, determining whether a tune-away associated with the first technology will occur, and outputting a Channel Quality Indicator (CQI) report corresponding to the second channel to transmit to the first network on the second channel using a second technology if the tune-away will occur, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

Description

CQI-based downlink buffer management

Priority based on 35U.S. C. ≡119

The present application claims priority and benefit from U.S. non-provisional application No. 16/674,724, filed on 5.11.2019, the entire contents of which are hereby expressly incorporated by reference.

Technical Field

Aspects of the present disclosure relate generally to wireless communications, and more particularly, to techniques for Channel Quality Indicator (CQI) -based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. A typical wireless communication system may use a multiple access technique capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access techniques include Code Division Multiple Access (CDMA) systems, time Division Multiple Access (TDMA) systems, frequency Division Multiple Access (FDMA) systems, orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, time division synchronous code division multiple access (TD-SCDMA) systems, and Long Term Evolution (LTE), to name a few.

The above multiple access techniques have been adopted in a variety of telecommunications standards to provide a common protocol that enables different user devices to communicate at the urban, national, regional and even global levels. Examples of emerging telecommunication standards for new radios (e.g., 5G NR). NR is an enhanced set of LTE mobile standards promulgated by 3 GPP. NR is designed to better support mobile broadband internet access by: improved spectral efficiency, reduced cost, improved service, utilization of new spectrum, and use of OFDMA with Cyclic Prefix (CP) on Downlink (DL) and Uplink (UL) are better integrated with other open standards. To this end, NR supports beamforming, multiple Input Multiple Output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to grow, there is a need for further improvements in LTE and NR technology. Preferably, these improvements should be applicable to other multiple access techniques and telecommunication standards employing these techniques.

Disclosure of Invention

The systems, methods, and devices of the present disclosure all have some aspects, but no single one of these aspects may be solely responsible for its desirable attributes. The following claims are in no way limiting to the scope of the present disclosure, some of which will now be discussed briefly. After careful consideration of these discussions, and particularly after reading the section entitled "detailed description" one will understand how the features of this disclosure provide advantages that include: improved downlink buffer management based on Channel Quality Indicators (CQI) and reduced throughput loss in dual connectivity with multiple SIMs.

Certain aspects provide a method for wireless communication of a User Equipment (UE). The method generally comprises: communicating with a first network on a first channel using a first technology; determining whether a tune-away associated with the first technology will occur; and if the tune-away is to occur, outputting a Channel Quality Indicator (CQI) report corresponding to the second channel for transmission to the first network on the second channel using a second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

Certain aspects provide an apparatus for wireless communication of a User Equipment (UE). The apparatus generally includes a processing system configured to: communicating with a first network on a first channel using a first technology; it is determined whether a tune-away associated with the first technique will occur. The apparatus generally further comprises an interface configured to: if the tune-away is to occur, a Channel Quality Indicator (CQI) report corresponding to the second channel is output for transmission to the first network on the second channel using a second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel. The apparatus generally also includes a memory coupled to the at least one processor.

Certain aspects provide an apparatus for wireless communication of a User Equipment (UE). The device generally comprises: means for communicating with a first network on a first channel using a first technology; determining whether a tune-away associated with the first technology will occur; and means for outputting a Channel Quality Indicator (CQI) report corresponding to the second channel to transmit to the first network on the second channel using a second technique if the tune-away is to occur, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

Certain aspects provide a non-transitory computer-readable medium for wireless communication of a User Equipment (UE). The device generally includes instructions executable by the device to: communicating with a first network on a first channel using a first technology; determining whether a tune-away associated with the first technology will occur; and if the tune-away is to occur, outputting a Channel Quality Indicator (CQI) report corresponding to the second channel for transmission to the first network on the second channel using a second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

Certain aspects provide a user equipment for wireless communications. The user equipment generally includes a processing system configured to: communicating with a first network on a first channel using a first technology; it is determined whether a tune-away associated with the first technique will occur. The user equipment typically further comprises a transmitter configured to: ; and if the tune-away is to occur, outputting a Channel Quality Indicator (CQI) report corresponding to the second channel for transmission to the first network on the second channel using a second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

To the accomplishment of the foregoing and related ends, one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the application, briefly summarized above, may be had by reference to some aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the application may admit to other equally effective aspects.

Fig. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

Fig. 2 is a block diagram conceptually illustrating the design of an example Base Station (BS) and User Equipment (UE), in accordance with certain aspects of the present disclosure.

Fig. 3A-3B illustrate different split bearer configurations, according to aspects of the present disclosure.

Fig. 4 provides an illustration of this packet loss problem due to a limited PDCP reordering buffer size, in accordance with certain aspects of the present disclosure.

Fig. 5 is a flowchart illustrating example operations for wireless communication by a UE, in accordance with certain aspects of the present disclosure.

Fig. 6 is a table depicting a table showing associations between channel quality indicator indexes and transport block sizes, in accordance with certain aspects of the present disclosure.

Fig. 7 illustrates a communication device that can include various components configured to perform the operations of the techniques disclosed herein, in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially employed in other aspects without specific recitation.

Detailed Description

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable media for Channel Quality Indicator (CQI) based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs. For example, in some cases, the techniques may involve: a "false" Channel Quality Indicator (CQI) is transmitted that is lower than the current CQI, resulting in no overload of the downlink buffer.

As noted, the following description provides examples of CQI-based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs, but is not limited to the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, replace, or add various procedures or components as desired. For example, the described methods may be performed in a different order than described, with various steps added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Furthermore, the scope of the present disclosure is intended to cover an apparatus or method that is implemented with other structures, functions, or both structures and functions than or in addition to the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of the invention. The term "exemplary" as used herein means "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular Radio Access Technology (RAT), which may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. Frequencies may also be referred to as carriers, subcarriers, frequency channels, tones, subbands, and so forth. Each frequency may support a single RAT in a given geographical area in order to avoid interference between wireless networks of different RATs. In some cases, a 5G NR RAT network may be deployed.

Fig. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be implemented. For example, the wireless communication network 100 may be an NR system (e.g., a 5G NR network).

As shown in fig. 1, wireless communication network 100 may include a plurality of Base Stations (BSs) 110a-z (each also referred to herein individually or collectively as BSs 110) and other network entities. BS110 may provide communication coverage for a particular geographic area, sometimes referred to as a "cell," which may be stationary or may be moving according to the location of mobile BS 110. In some examples, BS110 may interconnect with each other and/or to one or more other BSs or network nodes (not shown) through various types of backhaul interfaces (e.g., direct physical connections, wireless connections, virtual networks, etc.) using any suitable transport network. In the example shown in fig. 1, BS110 a, BS110 b, and BS110 c may be macro BSs for macro cell 102a, macro cell 102b, and macro cell 102c, respectively. BS110 x may be a pico BS for pico cell 102 x. BS110 y and BS110 z may be femto BSs for femto cells 102y and 102z, respectively. The BS may support one or more cells. BS110 communicates with User Equipments (UEs) 120a-y (each also referred to herein individually or collectively as UEs 120) in wireless communication network 100. UEs 120 (e.g., 120x, 120y, etc.) may be dispersed throughout wireless communication network 100, and each UE 120 may be stationary or mobile.

According to certain aspects, BS 110 and/or UE 120 may be configured for Channel Quality Indicator (CQI) based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs, as explained below. For example, as shown in fig. 1, UE 120a includes tune away manager 122. In accordance with aspects of the present disclosure, in some cases, tune away manager 122a may be configured to perform one or more of the operations shown in fig. 5, as well as other operations described herein, for Channel Quality Indicator (CQI) based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs. For example, in some cases, tune away manager 122 may be configured to: if a tune-away is to occur, a Channel Quality Indicator (CQI) report corresponding to the second channel is output for transmission to the first network on the second channel using a second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

The wireless communication network 100 may also include relay stations (e.g., relay station 110 r), also referred to as repeaters, etc., that receive transmissions of data and/or other information from upstream stations (e.g., BS 110a or UE 120 r) and send transmissions of data and/or other information to downstream stations (e.g., UE 120 or BS 110), or relay transmissions between UEs 120, to facilitate communications between devices.

Network controller 130 may be coupled to a set of BSs 110 and provide coordination and control for these BSs 110. Network controller 130 may communicate with these BSs 110 via a backhaul. BS 110 may also communicate (e.g., directly or indirectly) with each other via a wireless backhaul or a wired backhaul.

Fig. 2 illustrates example components of BS 110a and UE 120a (e.g., in wireless communication network 100 of fig. 1) that may be used to implement aspects of the present disclosure.

At BS 110a, transmit processor 220 may receive data from data source 212 and control information from controller/processor 240. The control information may be for a Physical Broadcast Channel (PBCH), a Physical Control Format Indicator Channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a Physical Downlink Control Channel (PDCCH), a group common PDCCH (GC PDCCH), and the like. The data may be for a Physical Downlink Shared Channel (PDSCH) or the like. Processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, e.g., for a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a cell-specific reference signal (CRS). A Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if any, and provide output symbol streams to Modulators (MODs) 232a-232 t. Each modulator 232a-232t may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The downlink signals from modulators 232a-232t may be transmitted via antennas 234a-234t, respectively.

At UE 120a, antennas 252a-252r may receive the downlink signals from BS 110a and provide the received signals to demodulators (DEMODs) in transceivers 254a-254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 may obtain received symbols from all demodulators 254a-254r, perform MIMO detection on the received symbols, if any, and provide detected symbols. Receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for UE 120a to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at UE 120a, transmit processor 264 may receive data (e.g., for a Physical Uplink Shared Channel (PUSCH)) from data source 262, receive control information (e.g., for a Physical Uplink Control Channel (PUCCH)) from controller/processor 280, and process the data and control information. The transmit processor 264 may also generate reference symbols for reference signals (e.g., for Sounding Reference Signals (SRS)). The symbols from transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by a demodulator in transceivers 254a-254r (e.g., for SC-FDM, etc.), and transmitted to BS 110a. At BS 110a, the uplink signal from UE 120a may be received by antennas 234, processed by modulators 232, detected by MIMO detector 236 (if any), and further processed by receive processor 238 to obtain decoded data and control information transmitted by UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to a controller/processor 240.

Memories 242 and 282 may store data and program codes for BS 110a and UE 120a, respectively. The scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

Controller/processor 280 and/or other processors and modules at UE 120a may perform or direct the execution of processes for the techniques described herein for CQI based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs. For example, as shown in fig. 2, according to aspects described herein, controller/processor 280 of UE 120a includes a tune away manager 281, which may be configured to perform one or more of the operations shown in fig. 5, as well as other operations described herein, for Channel Quality Indicator (CQI) based downlink buffer management and mitigating throughput loss in dual connectivity with multiple SIMs. For example, in some cases, tune away manager 281 may be configured to: the method includes communicating with a first network on a first channel using a first technology, determining whether a tune-away associated with the first technology will occur, and outputting a Channel Quality Indicator (CQI) report corresponding to a second channel if the tune-away will occur, for transmission to the first network on the second channel using a second technology, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel. Although shown at a controller/processor, other components of UE 120a and BS 110a may also be used to perform the operations described herein.

Example CQI-based downlink buffer management

In some cases, two different subscriptions may be supported on the same device (such as a user device) and based on two separate Subscriber Identity Modules (SIMs) (referred to as multi-SIMs (MSIMs)). These subscriptions may be located on the same radio network or different radio networks and may have different subscription profiles and quality of service (QOS) requirements. Further, different subscriptions may provide services on the same or different Radio Access Technologies (RATs). In general, when performing operations on two different RATs, MSIM solutions use less resources than are required to do two independent solutions, with the goal of optimizing the use of resources (RF, MIP, etc.) and providing an enhanced user experience.

In some cases, there are different categories of Radio Frequency (RF) solutions for MSIM devices. For example, in some cases, a device may include a dual transceiver that may provide dual reception and dual access (DSDA). For example, in this case, each subscription may correspond to its own transceiver. In other cases, the device may comprise a single transceiver, where both subscriptions share the same radio resources. Most conventional dual subscription devices and solutions share a single transceiver due to RF complexity, cost and power consumption considerations.

As the deployment of 5G New Radios (NR) has advanced very much around the world, MSIM solutions now include a combination of 5g+4g/3G/2G RATs. The Rel15 3GPP standard defines two 5G solutions: non-independent (NSA) and independent 5G (SA). In a stand-alone 5G NR architecture, both the signaling network and the radio can be handled by the 5G core. In contrast, in a 5G NSA network, a Long Term Evolution (LTE) core network and LTE radio access may be used as anchor points for all signaling and mobility management while adding a new 5G carrier. This architecture is attractive for early deployment of 5G NR access systems because the network can reuse the traditional operational LTE evolved node bs (enbs) and Evolved Packet Cores (EPCs). Non-independent solutions are also attractive because they facilitate seamless migration of networks using existing LTE core networks from 4G to 5G.

Dual Connectivity (DC) has been introduced to allow UEs to connect to two different network points simultaneously for achieving higher throughput, reliability and mobility robustness. An evolved universal mobile telecommunications service terrestrial radio access network (EUTRAN) -NR dual connectivity (ENDC) is one form of dual connectivity using LTE and NR. In the ENDC mode and for non-independent implementations, the UE may be connected to the LTE eNB and the NR gNB. In some cases, the LTE eNB may act as a master node (MeNB) and the gNB may act as a secondary node (SgNB). Both nodes may interface with an Evolved Packet Core (EPC) in the user plane, but the master node may be directly connected to the EPC.

Depending on whether the system is independent or dependent, a variety of architectural options are available for dual connectivity. In an example NSA configuration, a split bearer configuration may be used where user data is split at a Packet Data Convergence Protocol (PDCP) and routed to LTE or NR or both. In some cases, there may be two variants of split bearer configurations: option 3 shown in fig. 3A and option 3X shown in fig. 3B. In option 3 of fig. 3A, the bearer may terminate at the MeNB 302 and the user data traffic is split at the PDCP layer 304 of the MeNB 302 and routed to LTE (e.g., to the MeNB 302) and NR (e.g., sgNB 306,306). In option 3X of fig. 3B, the bearer may terminate at SgNB 306 and the user data split at PDCP layer 308 of SgNB 306 and routed to LTE (e.g., meNB 302) and NR (e.g., sgNB 306). Both of these options in separate bearers may allow the network to utilize the bandwidths of LTE and NR to increase throughput capacity and reliability. The packet routing decision and data split between LTE and 5G NR may be determined based on a number of factors such as: channel conditions, traffic load balancing, buffer status, QOS requirements, and backhaul capacity of the network.

The dependent 5G MSIM may be configured as nsa+l/W/G and will be a new class of concurrent RAT solutions pushed out by the network. Due to the difference in MIMO requirements between the RF front-end architecture, carrier frequency, 5G radio and 4G radio, nsa+l/W/G devices may have 1 transceiver for lte+lte/W/G and one single transceiver for NR 5G radio. Furthermore, another possibility for concurrent RAT design is NR dual reception mode, where part or all of the diversity links are tuned away due to RF coexistence restrictions or for the second subscription radio.

In nsa+l/W/G (e.g., 4G/3G/2G) solutions with split bearer configuration (e.g., option 3 or 3X illustrated in fig. 3A and 3B, respectively), downlink data may be split between LTE and NR at the PDCP layer and Radio Link Control (RLC) packets routed to NR and LTE, respectively, as shown. In the nsa+l/W/G solution, for a user equipment with one transceiver for NR and one transceiver for lte+lte/W/G, the user equipment may have to suspend using the first technology of the first subscription (e.g., LTE) and tune away to allow the second subscription (e.g., L/W/G) to receive paging/perform measurement activities every Discontinuous Reception (DRX) cycle.

In this case, the user equipment may continue to receive data (such as 5G NR) via the second technology using the first subscription. Thus, the user equipment may encounter PDCP holes due to LTE tune-away, while NR downlink packets are received in sequence during the tune-away (e.g., because the user equipment is tuned to L/W/G). These LTE PDCP holes may result in out-of-order delivery of packets at the PDCP layer of the user equipment during each tune-away. Out-of-order data packets may be buffered in a PDCP reorder buffer in the user equipment to allow lower layers to recover packets lost during tune-away. For example, when the user equipment receives out-of-order PDCP packets, the out-of-order packets may be buffered and a PDCP reordering timer may be started. The user equipment may then attempt to recover PDCP packets lost during the tune-away (e.g., via lower layer HARQ recovery or RLC recovery). Once the PDCP reordering timer expires or the PDCP reordering buffer is full, the buffered packets may be forcefully flushed to an application layer of the user equipment. In some cases, the PDCP reordering buffer may ensure minimal PDCP packet loss and all packets (e.g., NR and LTE) are ordered before they are sent to the application layer.

However, since PDCP reordering buffer size is limited, when the UE tunes away to receive pages associated with a second subscription (e.g., L/W/G), there is a problem in that PDCP reordering buffer size may cause LTE packets to be dropped and unable to recover. For example, when the UE tunes away from LTE to monitor network activity associated with the second subscription, the UE may miss one or more LTE packets. When this occurs, the UE starts a PDCP reordering timer and attempts to receive one or more lost LTE packets. However, due to the high throughput of 5G NR, 5G NR packets received using the first subscription may fill the PDCP re-ordering buffer before the UE has an opportunity to receive one or more lost LTE packets. In this case, when the PDCP re-ordering buffer is full, the UE must flush the packets in the PDCP re-ordering buffer to the UE's application layer before receiving one or more lost LTE packets, which would otherwise result in the one or more lost LTE packets being discarded and unable to recover.

Fig. 4 provides an illustration of this packet loss problem due to limited PDCP reordering buffer size. For example, assume that the PDCP reordering buffer size is 5MB and a 5G network is scheduled on each downlink slot of 0.5ms, with downlink modulation of 27, 13 symbols, and 273 Resource Blocks (RBs) (e.g., for a 100MHz bandwidth). Based on current specifications, in this scenario, the transport block size per slot may be greater than 129KB. Thus, in this example, the PDCP reordering buffer can store up to 38 data packets (e.g., 5 MB/129 KB per packet).

In the 100% scheduling case, 38 NR packets can be scheduled in 19ms, because each packet can be scheduled in 1 slot (0.5 ms). Thus, beyond a tune away interrupt of 19ms, the UE must flush the packets with holes buffered in the PDCP reorder buffer to higher layers. For example, as shown in fig. 4, at time t0, the UE may be receiving both LTE and NR DL packets prior to LTE tune away. At t1, the UE performs tune-away from LTE to a second subscription (e.g., 4G, 3G, 2G) to receive pages or perform measurements. During tune away, LTE DL packets 1, 4, 7, 10 and 13 are lost because the LTE radio where the UE is in NSA is suspended while NR packets continue to be received using the first subscription, which results in five lost PDCP packets. At time t2, the UE starts a PDCP reordering timer due to lost PDCP packets and buffers any received out-of-order packets in a PDCP reordering buffer. As described above, the PDCP reordering timer is about 50-100ms. However, the PDCP reordering buffer may not be able to accommodate NR data exceeding 19ms and out-of-order packets buffered in the PDCP reordering buffer would have to be flushed before the PDCP reordering timer expires, which does not allow an opportunity for lower layer HARQ recovery. For example, as shown at t3, the UE may be caused to flush the PDCP reordering buffer and discard packets 1, 4, 7, 10, and 13 as the NR data fills the PDCP reordering buffer. Furthermore, after flushing, the PDCP window may move, resulting in lost packets not being recovered.

Thus, in this scenario, the hole (or lost packet) due to PDCP buffer flushing significantly affects the Transmission Control Protocol (TCP) of the UE. For example, in this case, TCP flow control and backoff may be triggered due to packet loss at each tune-away, resulting in severely impacted throughput. Thus, since it may not be easy to change PDCP re-ordering buffer size (e.g., without changing the physical hardware of the UE), aspects of the present disclosure provide techniques for reducing the number of dropped packets during tune-away, e.g., by reducing the number of out-of-order packets (e.g., NR packets) that need to be buffered after tune-away. In some cases, these techniques may involve: a "false" Channel Quality Indicator (CQI) report corresponding to the NR channel is sent, thereby reducing the number of NR packets received after the tune-away and avoiding premature PDCP re-ordering buffer filling.

Fig. 5 is a flow chart illustrating example operations 500 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 500 may be performed, for example, by a UE, such as the UE 120a in the wireless communication network 100, for Channel Quality Indicator (CQI) based downlink buffer management and to mitigate throughput loss in dual connectivity with multiple SIMs, as described herein. The operations 500 may be implemented as software components executing and running on one or more processors (e.g., the controller/processor 280 of fig. 2). Further, the transmission and reception of signals by the UE in operation 500 may be implemented, for example, by one or more antennas (e.g., antenna 252 of fig. 2). In certain aspects, the transmission and/or reception of signals by the UE may be implemented via a bus interface of one or more processors (e.g., controller/processor 280) that obtain and/or output the signals.

Operation 500 begins at 505 with communicating with a first network over a first channel using a first technique.

At 510, the UE determines whether tune-away associated with the first technology will occur.

At 515, if tune-away is to occur, the UE outputs a Channel Quality Indicator (CQI) report corresponding to the second channel for transmission to the first network on the second channel using the second technique, wherein the CQI report indicates a lower CQI for the second channel than a current CQI for the second channel.

As described above, aspects of the present disclosure provide techniques for reducing the number of dropped packets during tune-away, e.g., by reducing the number of out-of-order packets that need to be buffered after tune-away. For example, in some cases, aspects of the present disclosure provide techniques for CQI-based flow control whereby a UE transmits a "false" CQI that is lower than the current CQI that is actually present to reduce the number of out-of-order packets that need to be buffered after tuning away. Reducing the number of out-of-order packets sent may result in not reaching the size limit of the PDCP re-ordering buffer and allow the UE to recover any lost packets during tune-away.

For example, in some cases, the UE may communicate with the first network using a first technology (e.g., LTE) on a first channel. In some cases, the UE may communicate using a first technology based on a first subscription stored in a first SIM. The UE is also capable of communicating with the first network using a second technology (e.g., 5G) on a second channel, for example using a first subscription stored in the first SIM. In some cases, the first technology (e.g., LTE) and the second technology (e.g., 5G) may be configured to enable split bearer communications by sharing the same Packet Data Convergence Protocol (PDCP), e.g., using one of the configurations shown in fig. 3A and 3B. In addition, the UE can communicate with the second network using a third technology (e.g., 4G, 3G, and/or 2G) and a second subscription stored in the second SIM.

According to aspects, at some point in time, the UE may determine whether tune-away associated with the first technology will occur. For example, in some cases, the UE may determine that a tune-away associated with the first technology will occur and the UE needs to tune away from communicating with the first network using the first technology to communicating with the second network using a third technology (e.g., 4G, 3G, and/or 2G) on a third channel. As described above, during the tune away, the UE may continue to communicate with the first network using a second technique (e.g., 5G NR). In some cases, the UE may determine to tune away based on scheduling measurements and/or received pages for the second subscription/third technique.

Thus, in response to a determination as to whether tune-away will occur (e.g., when the UE determines that tune-away will occur), the UE may send a CQI report to the first network indicating a lower CQI for the second channel corresponding to the second technology (e.g., 5G NR) than the current CQI actually present for the second channel. In some cases, sending a CQI report indicating a lower CQI may be based on a determination as to whether an application communicating using a second technology on a second channel is using a transmission control protocol and a non-independent subscription. For example, in response to tuning away and determining that the application is using the transmission control protocol and the non-independent subscription, the UE may continue to determine a lower CQI.

In some cases, transmitting a CQI report indicating a lower CQI may be based on: determining that the scheduling throughput associated with the second technique is above a threshold results in the PDCP reordering buffer being filled prematurely during the tune-away. For example, in some cases, the UE may monitor at least one of the following when making the determination: the current CQI associated with the second channel, the scheduling rate associated with the second technique, or the remaining packet reordering buffer size of the UE. Based on the monitoring, the UE may determine a scheduled throughput corresponding to the second technology based at least in part on at least one of a current CQI or a scheduled rate associated with the second technology. Additionally, in some cases, the UE may determine a duration corresponding to the tune away.

Thereafter, the UE may determine whether the remaining packet reordering buffer size of the UE is sufficient to store one or more packets received from the first network during the tune-away using the second technique. For example, in some cases, the determination as to whether the remaining packet reordering buffer size is sufficient may be based at least in part on at least one of a scheduled throughput corresponding to the second technique or a duration corresponding to the tune-away. For example, according to aspects, when a scheduled throughput corresponding to the second technique multiplied by a duration corresponding to the tune-away is less than a remaining packet reordering buffer size, the UE may determine that the remaining packet reordering buffer size is sufficient to store one or more packets received during the tune-away using the second technique.

However, when the scheduled throughput corresponding to the second technique multiplied by the duration corresponding to the tune-away is greater than the remaining packet reordering buffer size, the UE may determine that the remaining packet reordering buffer size is insufficient to store one or more packets received during the tune-away using the second technique. Thus, in this case, the UE determines a lower CQI based at least in part on determining that the remaining packet re-ordering buffer size of the UE is insufficient.

For example, when the UE determines that the remaining packet re-ordering buffer size of the UE is insufficient to store one or more packets received from the first network during the tune-away using the second technique, the UE may determine a lower CQI such that the one or more packets received via the second technique during the tune-away do not exceed the remaining packet re-ordering buffer size of the UE. That is, for example, the UE may determine a CQI that will result in a reduction in the transport block size associated with the second technique such that one or more packets received via the second technique during tune-away do not exceed the buffer size of the remaining packet reordering UE. In some cases, the determination regarding CQI may be based at least in part on at least one of: the current CQI, a scheduling rate associated with the second technique, a remaining packet re-ordering buffer size for the UE, a tune-away time corresponding to the tune-away, a duration corresponding to the tune-away, or a period corresponding to the tune-away.

For example, as shown in table 600 shown in fig. 6, each CQI index may be associated with a particular transport block size in bytes. For example, as shown in fig. 6, a CQI index of 9 may be associated with a TBS of 69,677 bytes. Thus, the UE can determine the scheduled throughput for any given CQI index. Thus, since the UE is already aware of the tune-away duration and the remaining packet re-ordering buffer size (e.g., as described above), the UE may determine the CQI that will result in a decrease in TBS such that the size corresponding to one or more packets received during the tune-away is less than the remaining packet re-ordering buffer size. For example, in some cases, the UE may determine the CQI according to the following scenario: the remaining packet reordering buffer size is ≡tbs current scheduling rate x duration of modification associated with lower CQI. In some cases, the UE may determine a lower CQI by using a lookup table (e.g., table 600 shown in fig. 6). For example, in some cases, the UE may determine a modified TBS associated with a lower CQI from table 600 shown in fig. 6.

Thus, once the UE determines a lower CQI that results in an appropriate TBS reduction, the UE may send a CQI report corresponding to the second channel to the first network on the second channel using the second technique, which indicates the lower CQI for the second channel. In some cases, the UE may output and send CQI reports to the first network (e.g., 5G nb) on the second channel using the second technique before the tune away occurs. In response to the lower CQI indicated in the CQI report, the first network may reduce the TBS size corresponding to the second technique, resulting in a reduced number of packets transmitted using the second technique.

Thereafter, in some cases, the UE may perform tune away to communicate with the second network using the third technology and the second subscription. In some cases, the third technology includes one of a fourth generation (4G) technology, a third generation (3G) technology, or a second generation (2G) technology. According to aspects, during tune away, the UE may detect one or more lost packets associated with a first technology (e.g., LTE) while continuing to receive one or more packets using a second technology (e.g., 5G NR). In this case, based on one or more lost packets, the UE may start a PDCP reordering timer that provides the UE with an amount of time to recover these lost packets before flushing the reordering buffer is needed. After starting the reordering timer, the UE may further receive one or more out-of-order packets from the first network during tune away using a second technique. The UE may then store the one or more out-of-order packets received from the first network using the second technique in a packet reordering buffer of the UE. According to aspects, since the UE reports a lower CQI, one or more out-of-order packets received from the first network using the second technique may therefore, and advantageously, not exceed a size limit of the packet re-ordering buffer (e.g., the remaining packet re-ordering buffer size).

According to aspects, after the UE completes performing the tune-away, the UE may return to communicating with the first network using the first technology. For example, in some cases, the UE may receive at least one packet from the first network using a first technique. In some cases, the at least one packet received using the first technique may include: one or more lost packets detected during tune away. Advantageously, since the UE reports a lower CQI, which in turn reduces the size of one or more packets received from the first network using the second technique, the UE is able to receive one or more lost packets before the reordering timer expires and before the size limit of the packet reordering buffer is exceeded. Thus, after receiving one or more lost packets from the first network, the UE may reorder the one or more lost packets from the first network and flush the reordered one or more lost packets received from the first network to the application layer of the UE.

In addition, after the tune away is completed, the UE may return to normal CQI operation, for example, by transmitting a CQI report for the second channel reflecting the current CQI corresponding to the second channel. Thereafter, upon detecting the next tune-away, the UE may repeat the techniques described above to report a lower CQI.

In addition to advantageously reducing the number of dropped packets, the techniques presented herein may also include other benefits of the english dual receive architecture, such as tuning some or all diversity links away when the 5G NR is in dual receive mode. For example, in this case, the UE may demodulate 5G NR data with a smaller number of receive chains during tune away, thus reducing CQI for 5G NR prior to tune away, increasing the chance of decoding 5G NR data during tune away. Since the UE can resume normal CQI reporting after tune away, the UE can resume 5G NR demodulation with all receive chains after tune away.

Fig. 7 illustrates a communication device 700 that may include various components (e.g., corresponding to functional unit components) configured to perform operations of the techniques disclosed herein (e.g., the operations shown in fig. 5). The communication device 700 includes a processing system 702 coupled to a transceiver 708. The transceiver 708 is configured to transmit and receive signals (e.g., the various signals described herein) for the communication device 700 via the antenna 710. The processing system 702 may be configured to perform processing functions for the communication device 700, including processing signals received and/or transmitted by the communication device 700.

The processing system 702 includes a processor 704 coupled to a computer readable medium/memory 712 via a bus 706. In certain aspects, the computer-readable medium/memory 712 is configured to store instructions (e.g., computer-executable code) that, when executed by the processor 704, cause the processor 704 to perform the operations shown in fig. 5, as well as other operations for performing the various techniques discussed herein, for Channel Quality Indicator (CQI) based downlink buffer management and to mitigate throughput loss in dual connectivity with multiple SIMs. In certain aspects, the computer-readable medium/memory 712 stores code for performing the operations shown in fig. 5, as well as for performing other operations of the various techniques discussed herein, for Channel Quality Indicator (CQI) based downlink buffer management and to mitigate throughput loss in dual connectivity with multiple SIMs. For example, computer readable medium/memory 712 stores: code 714 for communicating; code 716 for determining; code 718 for outputting; code 720 for monitoring; code 722 for executing; code 724 for detecting; code 726 for starting; code 728 for receiving; code 730 for storing; code 732 for reordering; and code 734 for flushing.

In certain aspects, the processor 704 may include circuitry configured to implement code stored in the computer-readable medium/memory 712, e.g., for performing the operations shown in fig. 5, as well as for performing other operations of the various techniques discussed herein, for Channel Quality Indicator (CQI) based downlink buffer management and to mitigate throughput loss in dual connectivity with multiple SIMs. For example, the processor 704 includes: circuitry 736 for communicating; circuitry 738 for determining; a circuit 740 for outputting; circuitry 742 for monitoring; circuitry 744 for performing; circuitry 746 for detection; a circuit for starting 748; a circuit 750 for receiving; a circuit 752 for storing; a circuit 754 for reordering; and a circuit 756 for flushing.

The techniques described herein may be used for various wireless communication techniques such as NR (e.g., 5G NR), 3GPP Long Term Evolution (LTE), LTE-advanced (LTE-A), code Division Multiple Access (CDMA), time Division Multiple Access (TDMA), frequency Division Multiple Access (FDMA), orthogonal Frequency Division Multiple Access (OFDMA), single-carrier frequency division multiple access (SC-FDMA), time division synchronous code division multiple access (TD-SCDMA), and other networks. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), CDMA 2000, and the like. UTRA includes Wideband CDMA (WCDMA) and other variations of CDMA. cdma 2000 covers the IS-2000, IS-95 and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications (GSM). An OFDMA network may implement radio technologies such as NR (e.g., 5G RA), evolved UTRA (E-UTRA), ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, flash-OFDMA, and so forth. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS). LTE and LTE-a are release of UMTS using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-a and GSM are described in documents from an organization named "third generation partnership project" (3 GPP). Cdma 2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3 GPP 2). NR is an emerging wireless communication technology being developed.

The techniques described herein may be used for the wireless networks and radio technologies mentioned above and other wireless networks and radio technologies. For clarity of illustration, while aspects are described herein using terms commonly associated with 3G, 4G, and/or 5G wireless technologies, aspects of the present disclosure may also be applied to other generation-based communication systems.

In 3GPP, the term "cell" can refer to a coverage area of a Node B (NB) and/or an NB subsystem serving the coverage area, depending on the context in which the term is used. In an NR system, the terms "cell" and BS, next generation node B (gNB or gNodeB), access Point (AP), distributed Unit (DU), operator or transmission-reception point (TRP) may be used interchangeably. The BS may provide communication coverage for macro cells, pico cells, femto cells, and/or other types of cells. A macrocell can cover a relatively large geographic area (e.g., a few kilometers in radius) that allows UEs with service subscriptions to be able to access without restriction. The pico cell may cover a relatively small geographic area, allowing unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) that allows restricted access to UEs (e.g., UEs in a Closed Subscriber Group (CSG), UEs for users in the home, etc.) that have an association with the femto cell. The BS for the macro cell may be referred to as a macro BS. The BS for the pico cell may be referred to as a pico BS. The BS for the femto cell may be referred to as a femto BS or a home BS.

The UE may also be referred to as a mobile station, terminal, access terminal, subscriber unit, station, customer Premises Equipment (CPE), cellular telephone, smart phone, personal Digital Assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless telephone, wireless Local Loop (WLL) station, tablet computer, camera, gaming device, netbook, smartbook, superbook, household appliance, medical device or apparatus, biosensor/device, wearable device such as a smartwatch, smart garment, smart glasses, smart bracelet, smart jewelry (e.g., smart bracelet, etc.), entertainment device (e.g., music device, video device, satellite radio, etc.), vehicle component or sensor, smart meter/sensor, industrial manufacturing device, global positioning system device, or any other suitable device configured to communicate via a wireless or wired medium. Some UEs may be considered Machine Type Communication (MTC) devices or evolved MTC (eMTC) devices. For example, MTC and eMTC UEs include robots, drones, remote devices, sensors, meters, monitors, location tags, and the like that may communicate with a BS, another device (e.g., a remote device), or some other entity. The wireless node may provide a connection for a network or to a network (e.g., a wide area network such as the internet or a cellular network), for example, via a wired or wireless communication link. Some UEs may be considered internet of things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

Some wireless networks (e.g., LTE) utilize Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into a plurality (K) of orthogonal subcarriers, where these subcarriers are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Typically, modulation symbols are transmitted in the frequency domain using OFDM and in the time domain using SC-FDM. The interval between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may depend on the system bandwidth. For example, the spacing of the subcarriers may be 15kHz and the minimum resource allocation, which is referred to as a "resource block" (RB), may be 12 subcarriers (or 180 kHz). Thus, the nominal Fast Fourier Transform (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for a system bandwidth of 1.25, 2.5, 5, 10 or 20 megahertz (MHz), respectively. The system bandwidth may also be divided into subbands. For example, one sub-band may cover 1.08MHz (i.e., 6 RBs), and there may be 1, 2, 4, 8, or 16 sub-bands for a system bandwidth of 1.25, 2.5, 5, 10, or 20MHz, respectively. In LTE, the basic Transmission Time Interval (TTI) or packet duration is a 1ms subframe.

NR can utilize OFDM with CP on uplink and downlink and includes support for half duplex operation using TDD. In NR, the subframe is still 1ms, but the basic TTI is called slot. A subframe contains a variable number of slots (e.g., 1, 2, 4, 8, 16,... NR RBs are 12 consecutive frequency subcarriers. The NR may support a 15KHz base subcarrier spacing and other subcarrier spacings may be specified relative to the base subcarrier spacing (e.g., 30kHz, 60kHz, 120kHz, 240kHz, etc.). The symbol and slot lengths scale with subcarrier spacing. The CP length also depends on the subcarrier spacing. Beamforming may be supported and beam directions may be dynamically configured. MIMO transmission with precoding may also be supported. In some examples, MIMO configuration in DL may support up to 8 transmit antennas with multi-layer DL transmitting up to 8 streams and up to 4 streams per UE. In some examples, multi-layer transmission of up to 2 streams per UE may be supported. Aggregation of multiple cells up to 8 serving cells may be supported.

In some examples, access to the air interface may be scheduled. A scheduling entity (e.g., BS) allocates resources for communications between some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communications, the subordinate entity utilizes the resources allocated by the scheduling entity. The base station is not just the only entity acting as a scheduling entity. In some examples, a UE may act as a scheduling entity, may schedule resources for one or more subordinate entities (e.g., one or more other UEs), and other UEs may utilize the UE-scheduled resources for wireless communication. In some examples, the UE may act as a scheduling entity in a peer-to-peer (P2P) network and/or a mesh network. In a mesh network example, UEs may communicate directly with each other in addition to communicating with the scheduling entity.

In some examples, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Practical applications for such side-link communications may include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, internet of things (IoE) communications, mission critical grids, and/or various other suitable applications. In general, a sidelink signal may refer to a signal transmitted from one subordinate entity (e.g., UE 1) to another subordinate entity (e.g., UE 2) without relaying the communication through a scheduling entity (e.g., UE or BS), even though the scheduling entity may be used for scheduling and/or control purposes. In some examples, the licensed spectrum may be used to transmit the sidelink signal (as opposed to wireless local area networks that typically use unlicensed spectrum).

The methods disclosed herein comprise one or more steps or actions for achieving these methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the present invention. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the present invention.

As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover: a. b, c, a-b, a-c, b-c, and a-b-c, as well as any combination having a plurality of identical elements (e.g., a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b-b, b-b-c, c-c, and c-c-c, or any other ordering of a, b, and c).

As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, researching, querying (e.g., a lookup table, database, or other data structure), ascertaining, and the like. Further, "determining" may also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and so forth. Further, "determining" may also include parsing, selecting, establishing, and the like.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects as well. Accordingly, the present invention is not limited to the aspects shown herein, but is to be accorded the full scope consistent with the present disclosure, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more". The term "some" refers to one or more unless specifically stated otherwise. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, no disclosure herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. Furthermore, no claim should be construed in accordance with 35u.s.c. ≡112 paragraph 6, unless the component is explicitly recited as "functional module" or in the method claims, the component is recited as "functional step".

The various operations of the methods described above may be performed by any suitable unit capable of performing the corresponding functions. These units may include various hardware and/or software components and/or modules including, but not limited to: a circuit, an Application Specific Integrated Circuit (ASIC), or a processor. Generally, where operations are shown in the figures, these operations may have correspondingly paired functional module components numbered similarly.

Various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable Logic Device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

When implemented using hardware, one exemplary hardware configuration may include a processing system in a wireless node. The processing system may be implemented using a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including processors, machine-readable media, and bus interfaces. The bus interface may be used to connect network adapters and the like to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the physical layer. In the case of user terminal 120 (see fig. 1), a user interface (e.g., keyboard, display, mouse, joystick, etc.) may also be connected to the bus. The bus also links various other circuits such as clock sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. A processor may be implemented using one or more general-purpose processors and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry capable of executing software. Those of ordinary skill in the art will recognize how to best implement the described functionality of the processing system depending on the particular application and overall design constraints imposed on the overall system.

When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Software should be construed broadly to mean instructions, data, or any combination thereof, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or other terminology. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general-purpose processing, including the execution of software stored on a machine-readable storage medium. A computer readable storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. Or the storage medium may be integral to the processor. By way of example, the machine-readable medium may comprise a transmission line, a carrier wave modulated with data, and/or a computer-readable storage medium having stored thereon instructions separate from the wireless node, all of which may be accessed by a processor through a bus interface. Alternatively or additionally, the machine-readable medium, or any portion thereof, may be an integral part of the processor, e.g., as may be the case with a cache and/or general purpose register file. Examples of machine-readable storage media may include, for example, RAM (random access memory), flash memory, ROM (read only memory), PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), registers, a magnetic disk, an optical disk, a hard disk, or any other suitable storage medium, or any combination thereof. The machine-readable medium may be embodied in a computer program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer readable medium may include a plurality of software modules. These software modules include instructions that, when executed by a device, such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a reception module. Each software module may be located in a single storage device or may be distributed among multiple storage devices. For example, when a trigger event occurs, a software module may be loaded from the hard disk into RAM. During execution of the software module, the processor may load some of these instructions into the cache to increase access speed. Subsequently, one or more cache lines may be loaded into a general purpose register file for execution by the processor. When referring to the functionality of the software modules below, it should be understood that the functionality is implemented by the processor when executing instructions from the software modules.

Further, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as Infrared (IR), radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and optical discOptical discs, where magnetic discs typically reproduce data magnetically, optical discs use laser light to reproduce data optically. Thus, in some aspects, a computer-readable medium may comprise a non-transitory computer-readable medium (e.g., a tangible medium). In addition, for other aspects, the computer-readable medium may include a transitory computer-readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

Accordingly, certain aspects may include a computer program product for performing the operations presented herein. For example, the computer program product may include a computer-readable medium having instructions stored thereon (and/or encoded with instructions) executable by one or more processors to perform the operations described herein (e.g., instructions for performing the operations described herein and illustrated in fig. 5, and for performing other operations of the various techniques discussed herein) for Channel Quality Indicator (CQI) based downlink buffer management and to mitigate throughput loss in dual connectivity with multiple SIMs.

Further, it should be appreciated that modules and/or other suitable elements for performing the methods and techniques described herein can be downloaded and/or obtained as desired by a user terminal and/or base station. For example, such a device may be coupled to a server to facilitate the implementation of means for transmitting information to perform the methods described herein. Or the various methods described herein may be provided by a storage unit (e.g., RAM, ROM, a physical storage medium such as a Compact Disc (CD) or floppy disk, etc.), such that the user terminal and/or base station may obtain the various methods when the storage unit is coupled to or provided to the device. In addition, any other suitable technique for providing the methods and techniques described herein to a device may also be utilized.

It should be understood that the invention is not limited to the precise arrangements and instrumentalities shown above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described hereinabove without departing from the scope of the invention.

Claims

1. An apparatus for wireless communication by a User Equipment (UE), comprising:

a processing system configured to:

communicating with a first network on a first channel using a first radio access technology; and

Communicating on a second channel using a second radio access technology;

Determining an occurrence of tune-away associated with the first radio access technology; and

An interface configured to:

Based at least in part on the determination of the occurrence of the tune-away, outputting a Channel Quality Indicator (CQI) report corresponding to the second channel for transmission on the second channel using the second radio access technology, wherein the CQI report indicates a lower CQI for the second channel than a CQI for the second channel prior to the occurrence of the tune-away;

Wherein the processing system is further configured to:

Monitoring at least one of the CQI prior to the occurrence of the tune away, a scheduling rate associated with the second radio access technology, or a remaining packet reordering buffer size for the UE;

Determining a scheduled throughput corresponding to the second radio access technology based at least in part on at least one of the CQI prior to the occurrence of the tune-away, the scheduling rate associated with the second radio access technology, or the remaining packet reordering buffer size of the UE;

Determining whether the remaining packet reordering buffer size of the UE is sufficient to store one or more packets to be received from the first network using the second radio access technology during the tune-away based at least in part on at least one of the scheduled throughput corresponding to the second radio access technology or a duration corresponding to the tune-away; and

The lower CQI is determined based at least in part on when the remaining packet reordering buffer size of the UE is insufficient to store one or more packets received from the first network during the tune-away using the second radio access technology.

2. The apparatus of claim 1, wherein to determine the lower CQI, the processing system is further configured to: a CQI is determined that will result in a reduction in a transport block size associated with the second radio access technology such that the one or more packets received via the second radio access technology during the tune-away do not exceed the remaining packet reordering buffer size of the UE.

3. The apparatus of claim 2, wherein the determination of the lower CQI is based at least in part on at least one of the CQI prior to the occurrence of the tune-away, the scheduling rate associated with the second radio access technology, the remaining packet reordering buffer size of the UE, a tune-away time corresponding to the tune-away, the duration corresponding to the tune-away, or a period corresponding to the tune-away.

4. The apparatus of claim 1, wherein the determination of the lower CQI comprises using a look-up table.

5. The apparatus of claim 1, wherein the processing system is further configured to:

determining whether an application communicating using the second radio access technology on the second channel is using a transmission control protocol and a non-independent subscription; and

The lower CQI is determined when the application is using the transmission control protocol and the dependent subscription.

6. The apparatus of claim 1, wherein the processing system is further configured to perform the tune-away to communicate with a second network using a third radio access technology, wherein the third radio access technology comprises one of a fourth generation (4G) radio access technology, a third generation (3G) radio access technology, or a second generation (2G) radio access technology.

7. The apparatus of claim 6, wherein during the tune-away, the processing system is further configured to:

Detecting one or more lost packets from the first network associated with the first radio access technology;

in response to detecting the one or more lost packets, starting a packet reordering timer;

During the tune away, receiving one or more out-of-order packets from the first network using the second radio access technology; and

The one or more out-of-order packets received from the first network using the second radio access technology are stored in a packet reordering buffer of the UE.

8. The apparatus of claim 7, wherein the one or more out-of-order packets do not exceed a size limit of the packet reordering buffer.

9. The apparatus of claim 7, wherein the processing system is further configured to:

receiving at least one packet from the first network using the first radio access technology before the tune away timer expires and before a size limit of the packet reordering buffer is exceeded, wherein the at least one packet comprises the one or more lost packets;

reordering the at least one packet from the first network; and

The reordered at least one packet received from the first network is flushed to an application layer of the UE.

10. The apparatus of claim 1, wherein the interface is configured to output the CQI report for transmission to the first network on the second channel using the second radio access technology before the tune-away occurs.

11. The apparatus of claim 1, wherein the first radio access technology comprises a Long Term Evolution (LTE) technology and the second radio access technology comprises a 5G New Radio (NR) technology.

12. The apparatus of claim 11, wherein the LTE technology and the 5G New Radio (NR) technology are configured for split bearer communication by sharing a same Packet Data Convergence Protocol (PDCP).

13. A method for wireless communication by a User Equipment (UE), comprising:

communicating with a first network on a first channel using a first radio access technology;

communicating on a second channel using a second radio access technology;

Wherein the method further comprises:

14. The method of claim 13, wherein the determining the lower CQI comprises: a CQI is determined that will result in a reduction in a transport block size associated with the second radio access technology such that the one or more packets received via the second radio access technology during the tune-away do not exceed the remaining packet reordering buffer size of the UE.

15. The method of claim 14, wherein the determining the lower CQI is based at least in part on at least one of the CQI prior to the occurrence of the tune-away, the scheduling rate associated with the second radio access technology, the remaining packet reordering buffer size of the UE, a tune-away time corresponding to the tune-away, the duration corresponding to the tune-away, or a period corresponding to the tune-away.

16. The method of claim 13, wherein determining the lower CQI comprises: a look-up table is used.

17. The method of claim 13, further comprising:

18. The method of claim 13, further comprising: the tune-away is performed to communicate with a second network using a third radio access technology, wherein the third radio access technology comprises one of a fourth generation (4G) radio access technology, a third generation (3G) radio access technology, or a second generation (2G) radio access technology.

19. The method of claim 18, wherein performing the tune-away comprises:

20. The method of claim 19, wherein the one or more out-of-order packets do not exceed a size limit of the packet reordering buffer.

21. The method of claim 19, further comprising:

reordering the at least one packet from the first network; and

22. The method of claim 13, wherein the CQI report is output for transmission to the first network on the second channel using the second radio access technology before the tune-away occurs.

23. The method of claim 13, wherein the first radio access technology comprises a Long Term Evolution (LTE) technology and the second radio access technology comprises a 5G New Radio (NR) technology.

24. The method of claim 23, wherein the LTE technology and the 5G New Radio (NR) technology are configured for split bearer communication by sharing a same Packet Data Convergence Protocol (PDCP).

25. An apparatus for wireless communication by a User Equipment (UE), comprising:

means for communicating with a first network on a first channel using a first radio access technology;

Means for communicating on a second channel using a second radio access technology;

wherein the apparatus further comprises:

means for monitoring at least one of the CQI prior to the occurrence of the tune away, a scheduling rate associated with the second radio access technology, or a remaining packet reordering buffer size for the UE;

Means for determining a scheduled throughput corresponding to the second radio access technology based at least in part on at least one of the CQI prior to the occurrence of the tune-away, the scheduling rate associated with the second radio access technology, or the remaining packet reordering buffer size of the UE;

The apparatus may include means for determining the lower CQI based at least in part on when the remaining packet reordering buffer size of the UE is insufficient to store one or more packets received from the first network during the tune away using the second radio access technology.

26. The apparatus of claim 25, wherein the first radio access technology comprises a Long Term Evolution (LTE) technology and the second radio access technology comprises a 5G New Radio (NR) technology.

27. A computer-readable medium for wireless communication, comprising instructions executable by an apparatus to:

Communicating on a second channel using a second radio access technology;

Determining whether an occurrence of a tune-away associated with the first radio access technology is to occur; and

wherein the computer-readable medium further comprises instructions executable by the apparatus to:

monitoring at least one of the CQI prior to the occurrence of the tune away, a scheduling rate associated with the second radio access technology, or a remaining packet reordering buffer size for a UE;

28. The computer-readable medium of claim 27, wherein the first radio access technology comprises a Long Term Evolution (LTE) technology and the second radio access technology comprises a 5G New Radio (NR) technology.